1. Field of the Invention
The present invention relates to a contact detecting device detecting that a user brings a finger, a pen or the like into contact with or proximity to a detecting surface. The present invention also relates to a display device having functions of the contact detecting device within a display section.
2. Description of the Related Art
A contact detecting device referred to as a so-called touch panel is known.
The contact detecting device is generally a device detecting that a finger of a user, a pen or the like comes into contact with or proximity to a detecting surface.
On the other hand, the touch panel is formed on a display panel, and enables information input as a substitute for ordinary buttons by making various buttons displayed as an image on a display surface. Application of this technology to a small mobile device enables a display and a button arrangement to be shared, and provides great advantages of increasing the size of the screen or saving the space of an operating section and reducing the number of parts.
Thus, the “touch panel” generally refers to a panel-shaped contact detecting device combined with a display device.
Three contact detecting systems of the touch panel are known, which are an optical type, a resistive film type, and a capacitance type.
To associate an electric change occurring in response to contact or proximity with positional information needs a large number of pieces of wiring combined so as to enable position identification and arranged in the form of a matrix.
To increase the resolution of detection by a manner of position detection with this wiring combination needs an enormous number of pieces of wiring.
Thus, in the three detecting systems mentioned above, a driving method that detects a contact position or a proximity position while scanning lines that output an electric change in one direction is becoming mainstream (see Hirotaka Hayashi etc., “Optical Sensor Embedded Input Display Usable under High-Ambient-Light Conditions,” SID 07 DIGEST p. 1105 (optical type), Bong Hyun You etc., “12.1-inch a-Si:H TFT LCD with Embedded Touch Screen Panel,” SID 08 DIGEST p. 830 (resistive film type), and Joohyung Lee etc., “Hybrid Touch Screen Panel Integrated in TFT-LCD,” SID 08 DIGEST p. 834 (capacitance type), hereinafter referred to as Non-Patent Documents 1 to 3, respectively, for example). A line in this case refers to a row in an X-direction or a Y-direction of minute sensor parts arranged two-dimensionally by a predetermined rule for contact detection.
When the touch panel is provided on the display panel, the thickness of a display module as a whole is increased.
Accordingly, the mainstream of developed types has recently changed from a touch panel mounted onto a display panel to a touch panel included within a display panel (see the above Non-Patent Documents 1 to 3 and Japanese Patent Laid-Open No. 2008-9750).
A “display device provided with a touch sensor” will hereinafter be used as a designation regardless of whether the touch panel is mounted onto a display panel or whether the touch panel is formed integrally with the display panel.